Sensor platform for noninvasive evaluation of pulmonary oxidative status.

We report on sensor platform including both the advanced nanostructured Prussian Blue based hydrogen peroxide sensor and the cooling-free breath aerosol (BA) condenser. The latter provides an order of magnitude more concentrated BA samples as compared to breath condensate collected traditionally through cooling; the conclusion is based on both: specimen's conductivity, the generally accepted dilution marker, and the evaluated HO levels (2.2-3.

[The comparative analysis of dorsopathy morbidity of adult population in the Russian Federation and separate Subjects of the Northern-West Federal Okrug in 2013-2022].

The dorsopathy is among of common causes of restriction of human life activity, affecting one's working capacity and quality of life. The purpouse of the study was to carry out comparative analysis of dorsopathy and spondylopathy morbidity of adult population in the Russian Federation and the Subjects of the Northern-West Federal Okrug in dynamics in 2013-2022. The statistical data of the Federal State Budget Institution "The Central Research Institute for Health Organization and Informatics of Minzdrav of Russia" was used.

Noninvasive Monitoring of Glycemia Level in Diabetic Patients by Wearable Advanced Biosensors.

We report on the possibility of noninvasive diabetes monitoring through continuous analysis of sweat. The prediction of the blood glucose level in diabetic patients is possible on the basis of their sweat glucose content due to the positive correlation discovered. The ratio between the blood glucose and sweat glucose concentrations for a certain diabetic subject is stable within weeks, excluding requirements for frequent blood probing.

[The application of information technologies in system of support of decision making in osteopathy].

The implementation of information technologies into treatment practice of modern health care significantly increases efficiency of diagnosis and treatment of dorsopathies. The purpose of the study is to develop software module to evaluate post-urological status of patients with spine dorsopathy to optimize diagnostic process and treatment planning. The article describes application of original software module to assess the post-urological status of patients with spine dorsopathy.

Fast Reaction of the Prussian Blue Based Nanozyme "Artificial Peroxidase" with the Substrates: Pre-Steady-State Kinetic Approach.

This letter introduces the pre-steady-state kinetic approach, which is traditional for evaluation of elementary constants in molecular (enzyme) catalysis, for nanozymes. Apparently, the most active peroxidase-mimicking nanozyme based on catalytically synthesized Prussian Blue nanoparticles has been chosen. The elementary constants () for the nanozymes' reduction by an electron-donor substrate (being the fastest stage according to steady-state kinetic data) have been determined by means of stopped-flow spectroscopy.

Polyazine nanoparticles as anchors of PQQ glucose dehydrogenase for its most efficient bioelectrocatalysis.

We report on the drop-cast production of glucose biosensors based on the most efficient bioelectrocatalysis by pyrroloquinoline quinone dependent glucose dehydrogenase (PQQ GDH). To orient the enzyme upon immobilization we suggest using poly(Methylene Green) (p(MG)) nanoparticles acting as anchors. Synthesis of polymeric anchors has been carried out in course of Methylene Green electropolymerization, which allowed to tune polymer-to-monomer ratio in the drop-cast mixtures varying the monomer concentration and applying different number of potential sweep cycles.

Pulse Power Generation Chronoamperometry as an Advanced Readout for (Bio)sensors: Application for Noninvasive Diabetes Monitoring.

We propose pulse power generation (PPG) amperometry as an advanced readout realized for Prussian blue (PB)-based (bio)sensors. In contrast to the conventional power generation mode, when the current response is generated upon continuous short-circuiting, the suggested pulse regime is fulfilled by periodic opening and shorting of the circuit. Despite PB being electroactive, the pulse readout is advantageous over conventional steady-state power generation, providing up to a 15-fold increased signal-to-background ratio as well as dramatically improved sensitivity exceeding 10 A·M·cm for HO sensors and 3.

Novel Siloxane Derivatives as Membrane Precursors for Lactate Oxidase Immobilization.

We report new enzyme-containing siloxane membranes for biosensor elaboration. Lactate oxidase immobilization from water-organic mixtures with a high concentration of organic solvent (90%) leads to advanced lactate biosensors. The use of the new alkoxysilane monomers-(3-aminopropyl)trimethoxysilane (APTMS) and trimethoxy[3-(methylamino)propyl]silane (MAPS)-as the base for enzyme-containing membrane construction resulted in a biosensor with up to a two times higher sensitivity (0.

Single Printing Step Prussian Blue Bulk-Modified Transducers for Oxidase-Based Biosensors.

We report on hydrogen peroxide sensors made through a single printing step with carbon ink containing catalytically synthesized Prussian blue nanoparticles. Despite their reduced sensitivity, the resulting bulk-modified sensors displayed both a wider linear calibration range (5 × 10-1 × 10 M) and an approximately four times lower detection limit versus the surface-modified sensors due to the dramatically decreased noise resulting in, on average, a six times higher signal-to-noise ratio. The corresponding glucose and lactate biosensors demonstrated similar and even higher sensitivities compared to those of biosensors based on surface-modified transducers.

Catalytically synthesized Prussian Blue nanozymes as labels for electrochemical DNA/RNA sensors.

We propose catalytically synthesized nanozymes based on Prussian Blue (PB) and azidomethyl-substituted poly (3,4-ethylenedioxythiophene) (azidomethyl-PEDOT) as novel electrocatalytic labels for DNA/RNA sensors. Catalytic approach allowed to synthesize highly redox and electrocatalytically active Prussian Blue nanoparticles functionalized with azide groups that enable 'click' conjugation with alkyne-modified oligonucleotides. Both competitive and sandwich-type schemes were realized.

Glucose test strips with the largest linear range made via single step modification by glucose oxidase-hexacyanoferrate-chitosan mixture.

We report on the amperometric second-generation glucose test strips with the linear calibration range covering blood glucose concentrations. Chitosan membrane was used for immobilization of both enzyme and mediator in a single step. Optimal chitosan concentration in membrane-forming mixture corresponds to the highest enzyme activity and dramatically improved mediator adsorption in final membrane.

Protein-sized nanozymes «artificial peroxidase» based on template catalytic synthesis of Prussian Blue.

We report on Prussian Blue based nanozymes, comparable in size with a natural enzyme peroxidase. Protein-sized nanoparticles have been synthesized in the course of reduction of ferric ion (Fe) and ferricyanide ([Fe(CN)]) one-to-one mixture in reversed micelles (isooctane|AOT|water) used as templates. Aniline chosen as the best reductant for this aim has led to formation of composite (according to Raman spectroscopy) Prussian Blue - polyaniline nanoparticles.

Prussian blue: from advanced electrocatalyst to nanozymes defeating natural enzyme.

The pathway from the advanced electrocatalyst to nanozymes defeating natural enzyme is reviewed. Prussian blue, being the most advantageous electrocatalyst for hydrogen peroxide reduction, is obviously the best candidate for mimicking peroxidase activity. Indeed, catalytically synthesized Prussian blue nanoparticles are characterized by the catalytic rate constants, which are significantly (up to 4 orders of magnitude) higher than for enzyme peroxidase.

Ultrastable Lactate Biosensor Linearly Responding in Whole Sweat for Noninvasive Monitoring of Hypoxia.

We report on the lactate biosensor with linear calibration range from 0.5 to 100 mM, which encircles possible levels of this metabolite concentration in both human sweat and blood. The linear calibration range at high analyte concentrations, which exceeds the Michaelis constant of lactate oxidase by several orders of magnitude, is provided by an additional perfluorosulfonated ionomer diffusion membrane.

Simultaneous monitoring of sweat lactate content and sweat secretion rate by wearable remote biosensors.

We report on the simultaneous monitoring of sweat lactate concentration and sweat secretion rate. For this aim lactate oxidase-Prussian Blue enzyme-nanozyme type lactate biosensors were elaborated. The use of siloxane-perfluorosulfonated ionomer composite membrane for enzyme-nanozyme immobilization results in the biosensor displaying flux independence in the whole range of physiological sweat secretion rates (0.

Flow-electrochemical synthesis of Prussian Blue based nanozyme 'artificial peroxidase'.

We report on fully electrochemical flow-through synthesis of Prussian Blue based nanozymes defeating peroxidase in terms of more than 200 times higher catalytic rate constant (k = 6 × 10 s). Being reagentless, reproducible, simple and scalable, the proposed approach blazes new trails for the electrosynthesis of functional conductive and electroactive nanomaterials.

Anchoring PQQ-Glucose Dehydrogenase with Electropolymerized Azines for the Most Efficient Bioelectrocatalysis.

Catalytic current of pyrroloquinoline quinone (PQQ)-glucose dehydrogenase (PQQ-GDH) immobilized over electropolymerized methylene green (MG) is increased only five times after the addition of the freely diffusing mediator. This value, being an efficiency criterion for bioelectrocatalysis, is several (three to six) times lower than that for the best reagentless glucose electrodes reported for this enzyme. Thermodynamics of the polyMG|PQQ-GDH electrode is determined by the enzyme-catalyzed reaction pointing to the direct bioelectrocatalysis.

Core-Shell Nanozymes "Artificial Peroxidase": Stability with Superior Catalytic Properties.

We report on the nanoparticles composed of the catalytically synthesized Prussian Blue (PB) core stabilized with the nickel hexacyanoferrate (NiHCF) shell. Catalyzing hydrogen peroxide reduction, the resulting nanozymes (ø = 66 nm) display catalytic rate constants, which for pyrogallol or ferrocyanide are, respectively, 25 and 35 times higher than those for peroxidase enzyme. After more than half a year of storage at a room temperature, the core-shell PB-NiHCF nanozymes retain both their size and physicochemical properties; such stability is unreachable for the enzymes.

Catalytic Pathway of Nanozyme "Artificial Peroxidase" with 100-Fold Greater Bimolecular Rate Constants Compared to Those of the Enzyme.

We report on the kinetic mechanism of the catalytically synthesized Prussian Blue nanoparticles denoted as "artificial peroxidase". In contrast to the enzyme, whose active site first interacts with hydrogen peroxide forming the so-called Compound I, in the case of the nanozymes, HO oxidizes their complex with reducing substrate. Slow release of the product (oxidized form of the latter) from the nanozymes has been registered.

Wearable non-invasive monitors of diabetes and hypoxia through continuous analysis of sweat.

We present here wearable devices for continuous monitoring of diabetes and hypoxia based on continuous analysis of sweat. To induce sweating the clinically relevant procedure (pilocarpine electrophoresis) is used. Being a sufficient requirement for diagnostics, positive correlations in variation rates between glucose and lactate concentrations in sweat and the corresponding values in blood are shown.

'Artificial peroxidase' nanozyme - enzyme based lactate biosensor.

In contrast to bienzyme biosensors, we propose the nanozyme-enzyme based ones substituting the enzyme peroxidase with the more active and stable nanoparticles "artificial peroxidase". The use of catalytically synthesized Prussian Blue based nanozymes simplifies assembling of hydrogen peroxide transducer providing its higher sensitivity. For immobilization of lactate oxidase the composite alkoxysilane - perfluorosulfonated ionomer (PFSI) membranes are proposed achieving the significantly improved operating stability.

Constant Potential Amperometric Flow-Injection Analysis of Ions and Neutral Molecules Transduced by Electroactive (Conductive) Polymers.

We first report on constant potential (dc) amperometric flow-injection analysis (FIA) transduced by electroactive (conductive) polymers. Amperometric response is caused by the polymer recharging in order to maintain the electrode potential at a constant level when (i) ions are crossing the film|solution interface and polarizing electrode|film interface or (ii) ions or neutral molecules are specifically interacting with the polymer recharging it. The response under constant solution flow is a current peak and in flow-injection mode is a couple of current peaks directed opposite of the first sharp, analytically valuable peak.

Noninvasive Diabetes Monitoring through Continuous Analysis of Sweat Using Flow-Through Glucose Biosensor.

We propose monitoring of diabetes through continuous analysis of undiluted sweat immediately after its excretion using a flow-through glucose biosensor. The used biosensors are based on Prussian Blue and glucose oxidase immobilized in perfluorosulfonated ionomer or gel of alkoxysilane; the resulting sensitivity with the latter reaches in batch mode 0.23 A M cm, and the calibration range is from 1 μM to 1 mM (flow-through mode).

Catalytically Synthesized Prussian Blue Nanoparticles Defeating Natural Enzyme Peroxidase.

We synthesized Prussian Blue (PB) nanoparticles through catalytic reaction involving hydrogen peroxide (HO) activation. The resulting nanoparticles display the size-dependent catalytic rate constants in HO reduction, which are significantly improved compared to natural enzyme peroxidase: for PB nanoparticles 200 nm in diameter, the turnover number is 300 times higher; for 570 nm diameter nanoparticles, it is 4 orders of magnitude higher. Comparing to the known peroxidase-like nanozymes, the advantages of the reported PB nanoparticles are their true enzymatic properties: (1) enzymatic specificity (an absence of oxidase-like activity) and (2) an ability to operate in physiological solutions.

Nonenzymatic Sensor for Lactate Detection in Human Sweat.

For noninvasive diagnostics of hypoxia, we propose the nonenzymatic sensor based on screen-printed structures with the working surface modified in course of electropolymerization of 3-aminophenylboronic acid (3-APBA) with imprinting of lactate. Impedimetric sensor allows lactate detection in the range from 3 mM to 100 mM with the detection limit of 1.5 mM; response time is 2-3 min.